Air conditioning system and defrosting control method thereof

Abstract

The invention relates to the technical field of air conditioners, in particular to an air conditioning system and a defrosting control method thereof, and aims to solve the problems that an existing air conditioning system is inaccurate in frosting judgment, false defrosting or the phenomenon that defrosting is advanced or lagged easily occurs, and the use experience of a user is affected. In order to achieve the purpose, the defrosting control method comprises the following steps that whether a defrosting mode is started or not is determined according to the heating capacity of an indoor unit and the temperature and humidity of an outdoor heat exchanger; and if the heating capacity of the indoor unit is reduced to exceed a first preset value, the humidity of the outdoor heat exchanger is larger than a second preset value, and the temperature of the outdoor heat exchanger is smaller than a third preset value, a defrosting mode is started. Whether the outdoor heat exchanger is frosted or not is jointly judged through the three conditions, the judgment result is accurate, the phenomenon of false defrosting or advanced or lagged defrosting is avoided, experience can be better guaranteed, and energy consumption is saved.

Description

Technical Field

[0001] The present invention relates to the technical field of air conditioning, and in particular provides an air conditioning system and a defrosting control method thereof. Background Art

[0002] When a multi-split air conditioner is defrosting, all outdoor units initiate defrost conditions and enter defrost mode. Existing technology requires shutting down the units and switching modes during defrost. When one or more units are operating and one of them reaches defrost conditions, it sends a "defrost request signal" to the main unit. Upon receiving the "defrost request" signal, the main unit sends a defrost command to all outdoor units, including those that are shut down. If all outdoor units enter defrost mode simultaneously, the indoor units will not blow hot or cold air, impacting the customer experience. Furthermore, the units must reverse direction, placing high demands on the system's reliability. Furthermore, reverse operation of the system increases energy consumption.

[0003] However, the existing technology has deficiencies in the judgment conditions for defrosting, and false defrosting or early or delayed defrosting may easily occur, affecting the user experience.

[0004] Therefore, the relevant field urgently needs an air-conditioning system and a control method thereof to solve the above technical problems. Summary of the Invention

[0005] The present invention aims to solve the above technical problems, namely, to solve the problem that the existing air-conditioning system has inaccurate judgment on frost, is prone to false defrosting or early or delayed defrosting, and affects the user experience.

[0006] In a first aspect, the present invention provides a defrost control method for an air conditioning system, the defrost control method comprising the following steps:

[0007] Determine whether to enter defrost mode based on the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger.

[0008] In a specific embodiment of the defrost control method for the air-conditioning system, “determining whether to enter the defrost mode based on the heating capacity of the indoor unit and the temperature and humidity of the outdoor heat exchanger” includes:

[0009] If the heating capacity of the indoor unit decreases by more than a first preset value, the humidity of the outdoor heat exchanger is greater than a second preset value, and the temperature of the outdoor heat exchanger is less than a third preset value, the defrost mode is entered.

[0010] In a specific embodiment of the defrost control method for the air-conditioning system, “determining whether to enter the defrost mode based on the heating capacity of the indoor unit and the temperature and humidity of the outdoor heat exchanger” includes:

[0011] If the heating capacity of the indoor unit does not decrease or does not decrease by more than a first preset value, the defrost mode is not entered.

[0012] In a specific embodiment of the defrost control method for the air-conditioning system, “determining whether to enter the defrost mode based on the heating capacity of the indoor unit and the temperature and humidity of the outdoor heat exchanger” includes:

[0013] If the humidity of the outdoor heat exchanger is not greater than the second preset value, the defrost mode is not entered.

[0014] In a specific embodiment of the defrost control method for the air-conditioning system, “determining whether to enter the defrost mode based on the heating capacity of the indoor unit and the temperature and humidity of the outdoor heat exchanger” includes:

[0015] If the temperature of the outdoor heat exchanger is not less than the third preset value, the defrost mode is not entered.

[0016] In a specific embodiment of the defrost control method for the air-conditioning system, it is determined whether the heating capacity of the indoor unit decreases by a first preset value according to the air outlet temperature and the set temperature of the indoor unit.

[0017] In a specific embodiment of the defrost control method for the air-conditioning system, a humidity detection element is provided at the outdoor heat exchanger for detecting the humidity of the outdoor heat exchanger to determine whether the humidity is greater than a second preset value.

[0018] In a specific embodiment of the defrost control method for the air-conditioning system, a temperature detection element is provided at the outdoor heat exchanger for detecting the temperature of the outdoor heat exchanger to determine whether the temperature of the outdoor heat exchanger is less than a third preset value.

[0019] In a specific implementation of the defrost control method for the air-conditioning system, the first preset value, the second preset value, and the third preset value are determined according to the current operating conditions of the air-conditioning system.

[0020] In a second aspect, the present invention provides an air-conditioning system, comprising a control module configured to execute the defrost control method for the air-conditioning system as described above.

[0021] When adopting the above technical solution, the defrost control method of the present invention includes the following steps: determining whether to enter defrost mode based on the heating capacity of the indoor unit and the temperature and humidity of the outdoor heat exchanger. Specifically, if the heating capacity of the indoor unit decreases by more than a first preset value, the humidity of the outdoor heat exchanger is greater than a second preset value, and the temperature of the outdoor heat exchanger is less than a third preset value, then defrost mode is entered. By using these three conditions to jointly determine whether frost has formed on the outdoor heat exchanger, the judgment result is relatively accurate, avoiding false defrosts or premature or delayed defrosts, thereby ensuring a better user experience and saving energy. BRIEF DESCRIPTION OF DRAWINGS

[0022] The preferred embodiments of the present application will be described below in conjunction with the accompanying drawings, in which:

[0023] Figure 1 is the main flow chart of the control method of the air conditioning system provided by the present application;

[0024] Figure 2 is the detailed step flow chart of the control method of the air conditioning system provided by the present application. DETAILED DESCRIPTION

[0025] The preferred embodiments of the present application will be described below in conjunction with the accompanying drawings. It should be understood by those skilled in the art that these embodiments are only used to explain the technical principles of the present application, and are not intended to limit the protection scope of the present application.

[0026] It should be noted that in the description of the present application, the terms indicating the direction or positional relationship of “up”, “down”, “left”, “right”, “inner”, “outer” and the like are based on the direction or positional relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, the terms “first” and “second” are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0027] In addition, it should also be noted that in the description of the present application, unless otherwise explicitly specified and limited, the terms “mounting”, “setting”, “connecting” should be understood broadly, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] The prior art has deficiencies in the judgment conditions for defrosting, which can easily cause false defrosting or defrosting in advance or lag, affecting the user's experience.

[0029] In order to solve the above technical problems, the present embodiment discloses an air-conditioning system, which is specifically a multi-split air-conditioning system. It includes an outdoor unit and multiple indoor units, and each indoor unit serves a specific area. Specifically, each indoor unit can serve a bedroom, a guest room or a bathroom, etc. This situation is mainly applied to hotel guest rooms; it is also applied to dormitories in factories or workshops. Each room has its own indoor unit, and the occupants can adjust the working mode and working temperature according to personal needs to ensure the comfort of each room. However. It is also possible to make multiple indoor units serve a living room, hall, dining room or office together. In this case, multiple indoor units will be arranged at intervals, each indoor unit serving a small area, and working together to serve the overall large area. Multiple indoor units are set in parallel and can be controlled independently so that they will not affect the operation of other indoor units. In addition, if the temperature in the areas served by multiple indoor units is uneven, in heating mode, if the temperature is too high, the heating capacity of the indoor units in the areas with excessively high temperatures will be reduced, specifically by reducing the air volume or the amount of refrigerant. In cooling mode, if the temperature is too high, the cooling capacity of the indoor units in the areas with excessively high temperatures will be adjusted, specifically by increasing the air volume or the amount of refrigerant. In cooling mode, if the temperature is too high, the cooling capacity of the indoor units in the areas with excessively high temperatures will be adjusted, specifically by increasing the air volume or the amount of refrigerant. In cooling mode, if the temperature is too low, the cooling capacity of the indoor units in the areas with excessively low temperatures will be adjusted, specifically by reducing the air volume or the amount of refrigerant.

[0030] The multi-connected air conditioning system can be a three-pipe heat recovery system. The outdoor unit has a high-pressure gas pipe main line, a low-pressure gas pipe main line and a liquid pipe main line. The first side of the indoor unit is connected to the liquid pipe main line, the second side is connected to the high-pressure gas pipe main line through a high-pressure branch line, and is connected to the low-pressure gas pipe main line through a low-pressure branch line. A high-pressure solenoid valve is arranged on the high-pressure branch line, and a low-pressure solenoid valve is arranged on the low-pressure branch line. The opening degree of the high-pressure solenoid valve and the low-pressure solenoid valve can be controlled to switch the indoor unit between the cooling mode and the heating mode. Since it is a three-pipe heat recovery system, the indoor unit can be switched between the cooling mode and the heating mode by controlling the opening degree of the high-pressure solenoid valve and the low-pressure solenoid valve. Different indoor units can be in different modes, that is, some indoor units can be in the cooling mode and the other indoor units can be in the heating mode. This multi-connected air conditioning system with heat recovery is mainly used in hotels and other comprehensive places, so that the guest rooms can be heated in winter, but the cold storage or machine room can be cooled in winter. The outdoor unit can include a plurality of outdoor heat exchangers, and the plurality of outdoor heat exchangers are connected in parallel. The outdoor unit can also be multiple, and the multiple outdoor units are also connected in parallel. An electronic expansion valve is arranged on the first side of the indoor unit. The amount of refrigerant flowing through the indoor heat exchanger of the indoor unit is controlled by the electronic expansion valve to adjust the heating or cooling capacity of the indoor unit, thereby adjusting the indoor temperature. In order to keep the high-pressure solenoid valve and the low-pressure solenoid valve stable and facilitate control, two valve boxes are usually provided, and the high-pressure solenoid valve and the low-pressure solenoid valve are two valves of the valve boxes. This arrangement facilitates control and protection of the valves. The outdoor unit can include a main unit and a plurality of sub-units according to needs, and the main unit and the sub-units are connected in parallel and connected to the high-pressure main line, the low-pressure main line and the liquid pipe main line through a four-way valve, and do not affect each other. The number of sub-units is determined according to the power of the sub-units and the maximum cooling or heating capacity of the air conditioning system, that is, according to the power of the sub-units and the number and power of the indoor units. The outdoor heat exchanger of the main unit and the sub-units can be one or multiple, which is determined according to the power of the sub-units and the main unit. In the heating mode, each outdoor heat exchanger of each outdoor unit needs to be monitored to determine whether frosting occurs.

[0031] The multi-connected air conditioning system can be a heat pump system. The outdoor unit has a first main line and a second main line. The two sides of the indoor unit are connected to the first main line and the second main line through branch lines. The working modes of the multiple indoor units are consistent, all in cooling mode or heating mode. Since there are only two main lines, the working mode of the indoor unit can only be switched by switching the working mode of the outdoor unit. An electronic expansion valve is arranged on one of the indoor units. The amount of refrigerant flowing through the indoor heat exchanger of the indoor unit is controlled by the electronic expansion valve to adjust the heating or cooling capacity of the indoor unit, thereby adjusting the indoor temperature. The outdoor unit can include a main unit and multiple sub-units according to the needs. The main unit and the sub-units are connected to the two main lines through a four-way valve and do not affect each other. The number of sub-units is determined according to the power of the sub-units and the maximum cooling or heating capacity of the air conditioning system, that is, according to the power of the sub-units and the number and power of the indoor units. The outdoor heat exchanger of the main unit and the sub-units can be one or multiple, which is determined according to the power of the sub-units and the main unit. In the heating mode, each outdoor heat exchanger of each outdoor unit needs to be monitored to determine whether frost occurs during defrosting monitoring.

[0032] Since the refrigerant used today is gradually replaced by flammable refrigerant, in order to avoid unnecessary safety hazards caused by refrigerant leakage, a stop valve is arranged at the indoor unit. Specifically, a stop valve is arranged on the liquid side of the heat recovery system indoor unit. When refrigerant leakage occurs in the indoor unit, the high-pressure electronic valve, the low-pressure electronic valve, and the stop valve are closed to cut off the refrigerant, so that the indoor unit no longer continues to leak, ensuring the safety of the indoor. For the heat pump system, a stop valve is installed on both sides of the indoor unit. When refrigerant leakage occurs in the indoor unit, the two stop valves are closed, so that the refrigerant cannot continue to leak.

[0033] A detection member, specifically a temperature sensor, is arranged at the air outlet of the indoor unit to detect the temperature of the air outlet to determine whether the temperature of the air outlet is consistent with the set temperature, and then determine whether the heating capacity of the indoor unit decreases. Whether the outdoor heat exchanger has frost or whether refrigerant leakage occurs can be determined by whether the heating capacity decreases. Whether the heating capacity of the indoor unit decreases can also be determined to determine whether the refrigerant circulating in the system decreases, and then determine whether refrigerant leakage occurs. In addition, whether the heat exchanger surface of the indoor unit is contaminated to cause a decrease in heat exchange capacity can also be determined by whether the heating capacity and the cooling capacity decrease.

[0034] It should be noted that although the temperature detection member is a temperature sensor in this embodiment, this is not a limitation of the present application. In other embodiments, it can also be a thermometer or an infrared temperature gun, which does not deviate from the basic principles of the present application and falls within the scope of the present application.

[0035] Specifically, according to the outlet air temperature and the set temperature of the indoor unit, it is determined whether the heating capacity of the indoor unit is reduced by a first preset value. Specifically, if the outlet air temperature is lower than the set temperature, the heating capacity is reduced. Here, lower does not mean that the heating capacity is reduced as long as it is lower. The set temperature can be set as a range value, and if it is lower than the lower limit of the range value, it is determined that the heating capacity is reduced. In the present embodiment, a is 1. It needs to be explained that although a is 1 in the present embodiment, this is not a limitation of the present application. Within the principle of the present application, a person skilled in the art can also choose a to be 1.5 or 2 in other embodiments, which does not deviate from the basic principle of the present application and falls within the protection scope of the present application.

[0036] The first preset value is determined according to the current working condition of the air conditioning system. Specifically, the heating capacity reduction value can be detected after the frosting condition under each working condition of the heating mode, and the first preset value is determined according to the reduction value. Specifically, it can be obtained through multiple tests. The test can be a real machine test, or it can be simulated and calculated through a data model, and then verified through a real machine test.

[0037] A temperature detection member is arranged at the outdoor heat exchanger of the outdoor unit, which is specifically a temperature sensor, for detecting the temperature of the outdoor heat exchanger. The temperature of the outdoor heat exchanger can be used to determine whether it is consistent with the set temperature, so as to determine whether the heat exchanger has frosting phenomenon, whether the air conditioning system has refrigerant leakage, and whether the heat exchange surface of the outdoor heat exchanger is polluted to cause the heat exchange capacity to be reduced. According to the detection of the temperature of the outdoor heat exchanger, it is determined whether the temperature of the outdoor heat exchanger is less than a third preset value. Specifically, the air conditioning system is in the heating mode, that is, the outdoor heat exchanger is in the mode of condenser. If the temperature of the outdoor heat exchanger is less than the third preset value, it is likely that the frosting phenomenon occurs to cause the temperature of the outdoor heat exchanger to be low. The third preset value is determined according to the current working condition of the air conditioning system. Specifically, the temperature of the outdoor heat exchanger can be detected after the frosting condition under each working condition of the heating mode, and the third preset value is determined according to the detected temperature. Specifically, it can be obtained through multiple tests. The test can be a real machine test, or it can be simulated and calculated through a data model, and then verified through a real machine test.

[0038] It needs to be explained that although the temperature detection member is a temperature sensor in the present embodiment, this is not a limitation of the present application. Within the principle of the present application, it can also be a thermometer or an infrared temperature gun in other embodiments, which does not deviate from the basic principle of the present application and falls within the protection scope of the present application.

[0039] The outdoor heat exchanger is also equipped with a humidity detector, specifically a humidity sensor, to detect humidity at the outdoor heat exchanger to determine whether the outdoor heat exchanger's heat exchange capacity has decreased, and further, whether the outdoor heat exchanger is frosted or contaminated. It can also determine whether the air conditioning system has a refrigerant leak. The detected humidity of the outdoor heat exchanger can be used to determine whether the humidity is greater than a second preset value. Specifically, when the air conditioning system is in heating mode, that is, when the outdoor heat exchanger is acting as a condenser, if the humidity of the outdoor heat exchanger is greater than the second preset value, it indicates that air circulation is not smooth and there is excessive moisture, which means that frosting is likely to have occurred. If the humidity is low and air flow is smooth, it indicates that the outdoor heat exchanger has not frosted, or the frost is minimal and does not affect the outdoor heat exchanger's heat exchange capacity. The second preset value is determined based on the current operating conditions of the air conditioning system. Specifically, the humidity of the outdoor heat exchanger can be detected under various operating conditions in heating mode, after frosting conditions have been detected, and the third preset value is determined based on the detected humidity. The specific results can be obtained through multiple tests. The tests can be actual machine tests, or they can be simulated and calculated through data models and then verified through actual machine tests.

[0040] It should be noted that regarding the humidity detection element, although it is a time period sensor in this embodiment, this is not a limitation of the present invention. Without departing from the principles of the present invention, in other embodiments, those skilled in the art may also choose it to be a hygrometer or other humidity detection device, which does not deviate from the basic principles of the present invention and will fall within the scope of protection of the present invention.

[0041] The air-conditioning system includes a control module configured to execute the defrost control method for the air-conditioning system. The control module is specifically disposed on the outdoor unit, more specifically, on the host computer of the outdoor unit, so that the entire air-conditioning system can be controlled by the control module. The control module is not only capable of executing the defrost control method for the air-conditioning system, but can also control whether the outdoor heat exchanger of the air-conditioning system operates as a condenser or an evaporator. It can also control the power of the compressor. In short, various operating parameters of the air-conditioning system can be controlled by the control module. Specifically, the control module can directly control the operation of each terminal, or the control module can control other control units, which in turn control the operation of each terminal.

[0042] Among them, such as Figure 1 As shown, in the heating mode, the defrost control method of the air-conditioning system includes the following main steps:

[0043] S1. Obtain the heating capacity of the indoor unit, specifically the heating capacity of multiple indoor units, and determine whether a decrease has occurred based on the heating capacity of the multiple indoor units to avoid misjudgment caused by a decrease in the heat exchange capacity of a single indoor unit due to contamination of the indoor heat exchanger surface by dirt.

[0044] S2, acquiring temperature and humidity of the outdoor heat exchanger;

[0045] S3, determining whether to enter the defrost mode according to the heating capacity of the indoor unit, the temperature and the humidity of the outdoor heat exchanger.

[0046] The "determining whether to enter the defrost mode according to the heating capacity of the indoor unit, the temperature and the humidity of the outdoor heat exchanger" comprises:

[0047] If the heating capacity of the indoor unit decreases by more than a first preset value, the humidity of the outdoor heat exchanger is greater than a second preset value, and the temperature of the outdoor heat exchanger is less than a third preset value, the defrost mode is entered. The heating capacity of the indoor unit decreases more seriously, which represents that the refrigerant temperature is lower and the heat exchange capacity of the outdoor heat exchanger is reduced. Moreover, the temperature of the outdoor heat exchanger is lower, which may have a frost phenomenon. In addition, the humidity of the outdoor heat exchanger is greater, which represents that the frost phenomenon may occur. If all the three conditions occur, it represents that the outdoor heat exchanger has frost, and defrosting is needed.

[0048] The "determining whether to enter the defrost mode according to the heating capacity of the indoor unit, the temperature and the humidity of the outdoor heat exchanger" further comprises:

[0049] If the heating capacity of the indoor unit does not decrease or does not decrease by more than the first preset value, the defrost mode is not entered. If the heating capacity does not decrease, it represents that the heat exchange capacity of the outdoor heat exchanger does not decrease, and thus the frost does not occur. If the decrease does not exceed the first preset value, the frost phenomenon may occur in the outdoor heat exchanger, but the frost is little and does not affect the normal work, and thus defrosting is not needed.

[0050] If the humidity of the outdoor heat exchanger is not greater than the second preset value, the defrost mode is not entered. The humidity of the outdoor heat exchanger is not greater than the second preset value, which represents that the humidity at the outdoor heat exchanger is small, the heat exchange is smooth, the air circulation is smooth, and the frost phenomenon does not occur.

[0051] If the temperature of the outdoor heat exchanger is not less than the third preset value, the defrost mode is not entered. The temperature of the outdoor heat exchanger is greater than the third preset value, which represents that the temperature of the outdoor heat exchanger is higher, and thus the frost phenomenon does not occur on the outer surface of the outdoor heat exchanger.

[0052] As shown in FIG. 1, the defrost control method of the air conditioning system comprises the following detailed steps: Figure 2

[0053] S11, acquiring the temperature of the air outlet of the indoor unit working in the heating mode;

[0054] S12, judging whether the temperature of the air outlet is lower than the set temperature. If yes, step S13 is performed. If no, the heating capacity of the indoor unit does not decrease, which represents that the frost phenomenon does not occur in the outdoor heat exchanger, and thus defrosting is not needed.​

[0055] S13, acquiring the humidity of the outdoor heat exchanger;

[0056] S14, judging whether the humidity of the outdoor heat exchanger is greater than a second preset value, if yes, proceeding to step S15; if no, the humidity of the outdoor heat exchanger is not high, which means that the outdoor heat exchanger has not appeared the frosting phenomenon, thus defrosting is not needed.

[0057] S15, acquiring the temperature of the outdoor heat exchanger;

[0058] S16, judging whether the temperature of the outdoor heat exchanger is less than a third preset value, if yes, proceeding to step S17; if no, the temperature of the outdoor heat exchanger is not too low, which means that the outdoor heat exchanger has not appeared the frosting phenomenon, thus defrosting is not needed.

[0059] S17, entering the defrosting mode to defrost the outdoor heat exchanger. Since the heating capacity of the indoor unit is reduced, the humidity of the outdoor heat exchanger is too large, and the temperature of the outdoor heat exchanger is too low, which means that the outdoor heat exchanger has appeared the frosting phenomenon, thus defrosting is needed.

[0060] If the outdoor unit includes multiple outdoor heat exchangers, the humidity and the temperature of each outdoor heat exchanger need to be detected to judge whether the corresponding outdoor heat exchanger has appeared the frosting phenomenon.

[0061] So far, the technical solution of the present application has been described in combination with the preferred embodiments shown in the drawings, but it is easy for those skilled in the art to understand that the protection scope of the present application is obviously not limited to these specific embodiments. Those skilled in the art can make equivalent changes or replacements to the related technical features without departing from the principles of the present application, and the technical solutions after these changes or replacements will all fall within the protection scope of the present application.

Claims

1. A defrosting control method of an air conditioning system, characterized by, The method comprises the following steps: According to the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger, it is determined whether to enter the defrosting mode.

2. The defrosting control method according to claim 1, characterized by, "According to the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger, it is determined whether to enter the defrosting mode" comprises: If the heating capacity of the indoor unit decreases by more than a first preset value, the humidity of the outdoor heat exchanger is greater than a second preset value, and the temperature of the outdoor heat exchanger is less than a third preset value, the defrosting mode is entered.

3. The defrosting control method according to claim 1, characterized by, "According to the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger, it is determined whether to enter the defrosting mode" comprises: If the heating capacity of the indoor unit does not decrease or does not decrease by more than the first preset value, the defrosting mode is not entered.

4. The defrosting control method according to claim 2 or 3, characterized by, According to the outlet air temperature and the set temperature of the indoor unit, it is determined whether the heating capacity of the indoor unit decreases by the first preset value.

5. The defrosting control method according to claim 1, characterized by, "According to the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger, it is determined whether to enter the defrosting mode" comprises: If the humidity of the outdoor heat exchanger is not greater than the second preset value, the defrosting mode is not entered.

6. The defrosting control method according to claim 2 or 5, characterized by, The outdoor heat exchanger is provided with a humidity detection member for detecting the humidity of the outdoor heat exchanger to determine whether the humidity is greater than the second preset value.

7. The defrosting control method according to claim 1, characterized by, "According to the heating capacity of the indoor unit, the temperature and humidity of the outdoor heat exchanger, it is determined whether to enter the defrosting mode" comprises: If the temperature of the outdoor heat exchanger is not less than the third preset value, the defrosting mode is not entered.

8. The defrosting control method according to claim 2 or 7, characterized by, The outdoor heat exchanger is provided with a temperature detection member for detecting the temperature of the outdoor heat exchanger to determine whether the temperature of the outdoor heat exchanger is less than the third preset value.

9. The defrost control method according to claim 2, wherein: The first preset value, the second preset value and the third preset value are determined according to the current working condition of the air conditioning system.

10. An air conditioning system characterized by, It comprises a control module configured to perform the defrosting control method of the air conditioning system as claimed in any one of claims 1-9.

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